Semiconductor device and method of forming shielding layer over semiconductor die mounted to TSV interposer

ABSTRACT

A semiconductor device has a plurality of conductive vias formed partially through a substrate. A conductive layer is formed over the substrate and electrically connected to the conductive vias. A semiconductor die is mounted over the substrate. An encapsulant is deposited over the semiconductor die and substrate. A trench is formed through the encapsulant around the semiconductor die. A shielding layer is formed over the encapsulant. The trench is formed partially through the substrate and the shielding layer is formed in the trench partially through the substrate. An insulating layer can be formed in the trench prior to forming the shielding layer. A portion of the substrate is removed to expose the conductive vias. An interconnect structure is formed over the substrate opposite the semiconductor die. The interconnect structure is electrically connected to the conductive vias. The shielding layer is electrically connected to the interconnect structure.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and,more particularly, to a semiconductor device and method of forming anEMI and RFI shielding layer over a semiconductor die mounted to a TSVinterposer.

BACKGROUND OF THE INVENTION

Semiconductor devices are commonly found in modern electronic products.Semiconductor devices vary in the number and density of electricalcomponents. Discrete semiconductor devices generally contain one type ofelectrical component, e.g., light emitting diode (LED), small signaltransistor, resistor, capacitor, inductor, and power metal oxidesemiconductor field effect transistor (MOSFET). Integrated semiconductordevices typically contain hundreds to millions of electrical components.Examples of integrated semiconductor devices include microcontrollers,microprocessors, charged-coupled devices (CCDs), solar cells, anddigital micro-mirror devices (DMDs).

Semiconductor devices perform a wide range of functions such as signalprocessing, high-speed calculations, transmitting and receivingelectromagnetic signals, controlling electronic devices, transformingsunlight to electricity, and creating visual projections for televisiondisplays. Semiconductor devices are found in the fields ofentertainment, communications, power conversion, networks, computers,and consumer products. Semiconductor devices are also found in militaryapplications, aviation, automotive, industrial controllers, and officeequipment.

Semiconductor devices exploit the electrical properties of semiconductormaterials. The atomic structure of semiconductor material allows itselectrical conductivity to be manipulated by the application of anelectric field or base current or through the process of doping. Dopingintroduces impurities into the semiconductor material to manipulate andcontrol the conductivity of the semiconductor device.

A semiconductor device contains active and passive electricalstructures. Active structures, including bipolar and field effecttransistors, control the flow of electrical current. By varying levelsof doping and application of an electric field or base current, thetransistor either promotes or restricts the flow of electrical current.Passive structures, including resistors, capacitors, and inductors,create a relationship between voltage and current necessary to perform avariety of electrical functions. The passive and active structures areelectrically connected to form circuits, which enable the semiconductordevice to perform high-speed calculations and other useful functions.

Semiconductor devices are generally manufactured using two complexmanufacturing processes, i.e., front-end manufacturing, and back-endmanufacturing, each involving potentially hundreds of steps. Front-endmanufacturing involves the formation of a plurality of die on thesurface of a semiconductor wafer. Each die is typically identical andcontains circuits formed by electrically connecting active and passivecomponents. The term “semiconductor die” as used herein refers to boththe singular and plural form of the word, and accordingly can refer toboth a single semiconductor device and multiple semiconductor devices.Back-end manufacturing involves singulating individual die from thefinished wafer and packaging the die to provide structural support andenvironmental isolation.

One goal of semiconductor manufacturing is to produce smallersemiconductor devices. Smaller devices typically consume less power,have higher performance, and can be produced more efficiently. Inaddition, smaller semiconductor devices have a smaller footprint, whichis desirable for smaller end products. A smaller die size can beachieved by improvements in the front-end process resulting in die withsmaller, higher density active and passive components. Back-endprocesses may result in semiconductor device packages with a smallerfootprint by improvements in electrical interconnection and packagingmaterials.

Another goal of semiconductor manufacturing is to produce higherperformance semiconductor devices. Increases in device performance canbe accomplished by forming active components that are capable ofoperating at higher speeds. In high frequency applications, such asradio frequency (RF) wireless communications, integrated passive devices(IPDs) are often contained within the semiconductor device. Examples ofIPDs include resistors, capacitors, and inductors. A typical RF systemrequires multiple IPDs in one or more semiconductor packages to performthe necessary electrical functions. However, high frequency electricaldevices generate or are susceptible to undesired electromagneticinterference (EMI) and radio frequency interference (RFI), or otherinter-device interference, such as capacitive, inductive, or conductivecoupling, also known as cross-talk, which can interfere with deviceoperation.

Semiconductor devices commonly use a metal shielding layer mounted to anencapsulant formed over the semiconductor die to reduce EMI and RFI. Theshield layer is typically electrically connected through a build-upinterconnect structure to a low impedance ground point to dissipate theEMI and RFI energy.

SUMMARY OF THE INVENTION

A need exists to isolate semiconductor die from EMI, RFI, and otherinter-device interference. Accordingly, in one embodiment, the presentinvention is a method of making a semiconductor device comprising thesteps of providing a substrate, forming a plurality of conductive viaspartially through the substrate, mounting a semiconductor die over thesubstrate, depositing an encapsulant over the semiconductor die andsubstrate, forming a trench through the encapsulant around thesemiconductor die, forming a shielding layer over the encapsulant,removing a portion of the substrate to expose the conductive vias, andforming an interconnect structure over the substrate opposite thesemiconductor die. The interconnect structure is electrically connectedto the conductive vias.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a substrate,forming a plurality of conductive vias in the substrate, mounting asemiconductor die over the substrate, depositing an encapsulant over thesemiconductor die and substrate, forming a trench through theencapsulant proximate to the semiconductor die, forming a shieldinglayer over the encapsulant, and forming an interconnect structure overthe substrate opposite the semiconductor die. The interconnect structureis electrically connected to the conductive vias.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a TSV substrate,mounting a semiconductor die over the TSV substrate, depositing anencapsulant over the semiconductor die and TSV substrate, forming atrench through the encapsulant proximate to the semiconductor die, andforming a shielding layer over the encapsulant and into the trench.

In another embodiment, the present invention is a semiconductor devicecomprising a substrate and plurality of conductive vias formed in thesubstrate. A semiconductor die is mounted over the substrate. Anencapsulant is deposited over the semiconductor die and substrate. Atrench is formed through the encapsulant proximate to the semiconductordie. A shielding layer is formed over the encapsulant. An interconnectstructure is formed over the substrate opposite the semiconductor die.The interconnect structure is electrically connected to the conductivevias.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a printed circuit board (PCB) with different types ofpackages mounted to its surface;

FIGS. 2 a-2 c illustrate further detail of the representativesemiconductor packages mounted to the PCB;

FIGS. 3 a-3 c illustrate a semiconductor wafer with a plurality ofsemiconductor die separated by a saw street;

FIGS. 4 a-4 k illustrate a process of forming an EMI and RFI shieldinglayer over a semiconductor die mounted to a TSV interposer;

FIG. 5 illustrates the EMI and RFI shielding layer over thesemiconductor die mounted to the TSV interposer;

FIGS. 6 a-6 f illustrate a process of forming an EMI and RFI shieldinglayer over a semiconductor die and extending into the TSV interposer;

FIG. 7 illustrates the EMI and RFI shielding layer extending into theTSV interposer;

FIG. 8 illustrates an insulating layer between the EMI and RFI shieldinglayer and encapsulant and TSV interposer;

FIG. 9 illustrates the EMI and RFI shielding layer electricallyconnected to the TSV interposer with conductive paste; and

FIG. 10 illustrates the semiconductor die with EMI and RFI shieldinglayer and TSV interposer mounted to a PCB.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

Semiconductor devices are generally manufactured using two complexmanufacturing processes: front-end manufacturing and back-endmanufacturing. Front-end manufacturing involves the formation of aplurality of die on the surface of a semiconductor wafer. Each die onthe wafer contains active and passive electrical components, which areelectrically connected to form functional electrical circuits. Activeelectrical components, such as transistors and diodes, have the abilityto control the flow of electrical current. Passive electricalcomponents, such as capacitors, inductors, resistors, and transformers,create a relationship between voltage and current necessary to performelectrical circuit functions.

Passive and active components are formed over the surface of thesemiconductor wafer by a series of process steps including doping,deposition, photolithography, etching, and planarization. Dopingintroduces impurities into the semiconductor material by techniques suchas ion implantation or thermal diffusion. The doping process modifiesthe electrical conductivity of semiconductor material in active devices,transforming the semiconductor material into an insulator, conductor, ordynamically changing the semiconductor material conductivity in responseto an electric field or base current. Transistors contain regions ofvarying types and degrees of doping arranged as necessary to enable thetransistor to promote or restrict the flow of electrical current uponthe application of the electric field or base current.

Active and passive components are formed by layers of materials withdifferent electrical properties. The layers can be formed by a varietyof deposition techniques determined in part by the type of materialbeing deposited. For example, thin film deposition can involve chemicalvapor deposition (CVD), physical vapor deposition (PVD), electrolyticplating, and electroless plating processes. Each layer is generallypatterned to form portions of active components, passive components, orelectrical connections between components.

The layers can be patterned using photolithography, which involves thedeposition of light sensitive material, e.g., photoresist, over thelayer to be patterned. A pattern is transferred from a photomask to thephotoresist using light. In one embodiment, the portion of thephotoresist pattern subjected to light is removed using a solvent,exposing portions of the underlying layer to be patterned. In anotherembodiment, the portion of the photoresist pattern not subjected tolight, the negative photoresist, is removed using a solvent, exposingportions of the underlying layer to be patterned. The remainder of thephotoresist is removed, leaving behind a patterned layer. Alternatively,some types of materials are patterned by directly depositing thematerial into the areas or voids formed by a previous deposition/etchprocess using techniques such as electroless and electrolytic plating.

Depositing a thin film of material over an existing pattern canexaggerate the underlying pattern and create a non-uniformly flatsurface. A uniformly flat surface is required to produce smaller andmore densely packed active and passive components. Planarization can beused to remove material from the surface of the wafer and produce auniformly flat surface. Planarization involves polishing the surface ofthe wafer with a polishing pad. An abrasive material and corrosivechemical are added to the surface of the wafer during polishing. Thecombined mechanical action of the abrasive and corrosive action of thechemical removes any irregular topography, resulting in a uniformly flatsurface.

Back-end manufacturing refers to cutting or singulating the finishedwafer into the individual die and then packaging the die for structuralsupport and environmental isolation. To singulate the die, the wafer isscored and broken along non-functional regions of the wafer called sawstreets or scribes. The wafer is singulated using a laser cutting toolor saw blade. After singulation, the individual die are mounted to apackage substrate that includes pins or contact pads for interconnectionwith other system components. Contact pads formed over the semiconductordie are then connected to contact pads within the package. Theelectrical connections can be made with solder bumps, stud bumps,conductive paste, or wirebonds. An encapsulant or other molding materialis deposited over the package to provide physical support and electricalisolation. The finished package is then inserted into an electricalsystem and the functionality of the semiconductor device is madeavailable to the other system components.

FIG. 1 illustrates electronic device 50 having a chip carrier substrateor printed circuit board (PCB) 52 with a plurality of semiconductorpackages mounted on its surface. Electronic device 50 can have one typeof semiconductor package, or multiple types of semiconductor packages,depending on the application. The different types of semiconductorpackages are shown in FIG. 1 for purposes of illustration.

Electronic device 50 can be a stand-alone system that uses thesemiconductor packages to perform one or more electrical functions.Alternatively, electronic device 50 can be a subcomponent of a largersystem. For example, electronic device 50 can be part of a cellularphone, personal digital assistant (PDA), digital video camera (DVC), orother electronic communication device. Alternatively, electronic device50 can be a graphics card, network interface card, or other signalprocessing card that can be inserted into a computer. The semiconductorpackage can include microprocessors, memories, application specificintegrated circuits (ASIC), logic circuits, analog circuits, RFcircuits, discrete devices, or other semiconductor die or electricalcomponents. Miniaturization and weight reduction are essential for theseproducts to be accepted by the market. The distance betweensemiconductor devices must be decreased to achieve higher density.

In FIG. 1, PCB 52 provides a general substrate for structural supportand electrical interconnect of the semiconductor packages mounted on thePCB. Conductive signal traces 54 are formed over a surface or withinlayers of PCB 52 using evaporation, electrolytic plating, electrolessplating, screen printing, or other suitable metal deposition process.Signal traces 54 provide for electrical communication between each ofthe semiconductor packages, mounted components, and other externalsystem components. Traces 54 also provide power and ground connectionsto each of the semiconductor packages.

In some embodiments, a semiconductor device has two packaging levels.First level packaging is a technique for mechanically and electricallyattaching the semiconductor die to an intermediate carrier. Second levelpackaging involves mechanically and electrically attaching theintermediate carrier to the PCB. In other embodiments, a semiconductordevice may only have the first level packaging where the die ismechanically and electrically mounted directly to the PCB.

For the purpose of illustration, several types of first level packaging,including bond wire package 56 and flipchip 58, are shown on PCB 52.Additionally, several types of second level packaging, including ballgrid array (BGA) 60, bump chip carrier (BCC) 62, dual in-line package(DIP) 64, land grid array (LGA) 66, multi-chip module (MCM) 68, quadflat non-leaded package (QFN) 70, and quad flat package 72, are shownmounted on PCB 52. Depending upon the system requirements, anycombination of semiconductor packages, configured with any combinationof first and second level packaging styles, as well as other electroniccomponents, can be connected to PCB 52. In some embodiments, electronicdevice 50 includes a single attached semiconductor package, while otherembodiments call for multiple interconnected packages. By combining oneor more semiconductor packages over a single substrate, manufacturerscan incorporate pre-made components into electronic devices and systems.Because the semiconductor packages include sophisticated functionality,electronic devices can be manufactured using cheaper components and astreamlined manufacturing process. The resulting devices are less likelyto fail and less expensive to manufacture resulting in a lower cost forconsumers.

FIGS. 2 a-2 c show exemplary semiconductor packages. FIG. 2 aillustrates further detail of DIP 64 mounted on PCB 52. Semiconductordie 74 includes an active region containing analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed within the die and are electricallyinterconnected according to the electrical design of the die. Forexample, the circuit can include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements formedwithin the active region of semiconductor die 74. Contact pads 76 areone or more layers of conductive material, such as aluminum (Al), copper(Cu), tin (Sn), nickel (Ni), gold (Au), or silver (Ag), and areelectrically connected to the circuit elements formed withinsemiconductor die 74. During assembly of DIP 64, semiconductor die 74 ismounted to an intermediate carrier 78 using a gold-silicon eutecticlayer or adhesive material such as thermal epoxy or epoxy resin. Thepackage body includes an insulative packaging material such as polymeror ceramic. Conductor leads 80 and bond wires 82 provide electricalinterconnect between semiconductor die 74 and PCB 52. Encapsulant 84 isdeposited over the package for environmental protection by preventingmoisture and particles from entering the package and contaminating die74 or bond wires 82.

FIG. 2 b illustrates further detail of BCC 62 mounted on PCB 52.Semiconductor die 88 is mounted over carrier 90 using an underfill orepoxy-resin adhesive material 92. Bond wires 94 provide first levelpackaging interconnect between contact pads 96 and 98. Molding compoundor encapsulant 100 is deposited over semiconductor die 88 and bond wires94 to provide physical support and electrical isolation for the device.Contact pads 102 are formed over a surface of PCB 52 using a suitablemetal deposition process such as electrolytic plating or electrolessplating to prevent oxidation. Contact pads 102 are electricallyconnected to one or more conductive signal traces 54 in PCB 52. Bumps104 are formed between contact pads 98 of BCC 62 and contact pads 102 ofPCB 52.

In FIG. 2 c, semiconductor die 58 is mounted face down to intermediatecarrier 106 with a flipchip style first level packaging. Active region108 of semiconductor die 58 contains analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed according to the electrical design of the die.For example, the circuit can include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements withinactive region 108. Semiconductor die 58 is electrically and mechanicallyconnected to carrier 106 through bumps 110.

BGA 60 is electrically and mechanically connected to PCB 52 with a BGAstyle second level packaging using bumps 112. Semiconductor die 58 iselectrically connected to conductive signal traces 54 in PCB 52 throughbumps 110, signal lines 114, and bumps 112. A molding compound orencapsulant 116 is deposited over semiconductor die 58 and carrier 106to provide physical support and electrical isolation for the device. Theflipchip semiconductor device provides a short electrical conductionpath from the active devices on semiconductor die 58 to conductiontracks on PCB 52 in order to reduce signal propagation distance, lowercapacitance, and improve overall circuit performance. In anotherembodiment, the semiconductor die 58 can be mechanically andelectrically connected directly to PCB 52 using flipchip style firstlevel packaging without intermediate carrier 106.

FIG. 3 a shows a semiconductor wafer 120 with a base substrate material122, such as silicon, germanium, gallium arsenide, indium phosphide, orsilicon carbide, for structural support. A plurality of semiconductordie or components 124 is formed on wafer 120 separated by inter-diewafer area or saw streets 126 as described above. Saw streets 126provide cutting areas to singulate semiconductor wafer 120 intoindividual semiconductor die 124. In one embodiment, semiconductor die124 may have dimensions ranging from 2×2 millimeters (mm) to 15×15 mm.

FIG. 3 b shows a cross-sectional view of a portion of semiconductorwafer 120. Each semiconductor die 124 has a back surface 128 and activesurface 130 containing analog or digital circuits implemented as activedevices, passive devices, conductive layers, and dielectric layersformed within the die and electrically interconnected according to theelectrical design and function of the die. For example, the circuit mayinclude one or more transistors, diodes, and other circuit elementsformed within active surface 130 to implement analog circuits or digitalcircuits, such as digital signal processor (DSP), ASIC, memory, or othersignal processing circuit. Semiconductor die 124 may also containintegrated passive devices (IPD), such as inductors, capacitors, andresistors, for RF signal processing. Semiconductor die 124 can be aflipchip type die, wire-bonded die, or conductive through silicon via(TSV) die.

An electrically conductive layer 132 is formed over active surface 130using PVD, CVD, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 132 can be oneor more layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 132 operates as contact padselectrically connected to the circuits on active surface 130. Contactpads 132 can be disposed side-by-side a first distance from the edge ofsemiconductor die 124, as shown in FIG. 3 b. Alternatively, contact pads132 can be offset in multiple rows such that a first row of contact padsare disposed a first distance from the edge of the die, and a second rowof contact pads alternating with the first row are disposed a seconddistance from the edge of the die.

An electrically conductive bump material is deposited over contact pads132 using an evaporation, electrolytic plating, electroless plating,ball drop, or screen printing process. The bump material can be Al, Sn,Ni, Au, Ag, Pb, Bi, Cu, solder, and combinations thereof, with anoptional flux solution. For example, the bump material can be eutecticSn/Pb, high-lead solder, or lead-free solder. The bump material isbonded to contact pad 132 using a suitable attachment or bondingprocess. For example, the bump material can be compression bonded tocontact pad 132. The bump material can also be reflowed by heating thematerial above its melting point to form spherical balls or bumps 134.In some applications, bumps 134 are reflowed a second time to improveelectrical contact to contact pad 132. Bumps 134 represent one type ofinterconnect structure that can be formed over contact pad 132. Theinterconnect structure can also use stud bump, micro bump, or otherelectrical interconnect.

In FIG. 3 c, semiconductor wafer 120 is singulated through saw street126 using a saw blade or laser cutting tool 136 into individualsemiconductor die 124.

FIGS. 4 a-4 k illustrate, in relation to FIGS. 1 and 2 a-2 c, a processof forming an EMI and RFI shielding layer over a semiconductor diemounted to a TSV interposer. In FIG. 4 a, a wafer-level substrate orinterposer 140 contains base material such as silicon, germanium,gallium arsenide, indium phosphide, silicon carbide, or other suitablematerial for structural support.

In FIG. 4 b, a plurality of vias is formed partially through interposer140 using mechanical drilling, laser drilling, or deep reactive ionetching (DRIE). In one embodiment, the vias are cut through 60% of thethickness of interposer 140. The vias are filled with Al, Cu, Sn, Ni,Au, Ag, Ti, (W), poly-silicon, or other suitable electrically conductivematerial using electrolytic plating, electroless plating process, orother suitable deposition process to form z-direction blind conductivethrough silicon vias (TSV) 142.

An electrically conductive layer or redistribution layer (RDL) 144 isformed over surface 146 of TSV interposer 140 using a patterning andmetal deposition process such as sputtering, electrolytic plating, andelectroless plating. Conductive layer 144 can be one or more layers ofAl, Cu, Sn, Ni, Au, Ag, or other suitable electrically conductivematerial. One portion of conductive layer 144 is electrically connectedto conductive TSVs 142. Other portions of conductive layer 144 can beelectrically common or electrically isolated depending on the design andfunction of semiconductor die 124.

In FIG. 4 c, semiconductor die 124 from FIGS. 3 a-3 c are mounted to TSVinterposer 140 using a pick and place operation with active surface 130and bumps 134 oriented toward the TSV interposer. FIG. 4 d showssemiconductor die 124 mounted to TSV interposer 140. Bumps 134 areelectrically connected to conductive layer 144 and conductive TSVs 142.

In FIG. 4 e, an encapsulant or molding compound 150 is deposited overTSV interposer 140 and semiconductor die 124 using a paste printing,compressive molding, transfer molding, liquid encapsulant molding,vacuum lamination, spin coating, or other suitable applicator.Encapsulant 150 can be polymer composite material, such as epoxy resinwith filler, epoxy acrylate with filler, or polymer with proper filler.Encapsulant 150 is non-conductive and environmentally protects thesemiconductor device from external elements and contaminants.

In FIG. 4 f, a trench or channel 152 is cut completely throughencapsulant 150 and terminating at TSV interposer 140 using saw blade orlaser cutting tool 154. FIG. 4 g shows a top view of trench 152 formedin encapsulant 150 around the peripheral area of semiconductor die 124.

Semiconductor die 124 may contain baseband circuits that generate EMI,RFI, or other inter-device interference, such as capacitive, inductive,or conductive coupling. In other embodiments, semiconductor die 124contain IPDs that are susceptible to EMI, RFI, and inter-deviceinterference. For example, the IPDs contained within semiconductor die124 provide the electrical characteristics needed for high frequencyapplications, such as resonators, high-pass filters, low-pass filters,band-pass filters, symmetric Hi-Q resonant transformers, and tuningcapacitors. The IPDs can be used as front-end wireless RF components,which can be positioned between the antenna and transceiver. The IPDinductor can be a hi-Q balun, transformer, or coil, operating up to 100Gigahertz. In some applications, multiple baluns are formed on a samesubstrate, allowing multi-band operation. For example, two or morebaluns are used in a quad-band for mobile phones or other global systemfor mobile (GSM) communications, each balun is dedicated for a frequencyband of operation of the quad-band device. A typical RF system requiresmultiple IPDs and other high frequency circuits in one or moresemiconductor packages to perform the necessary electrical functions.

To reduce the effects of EMI and RFI, a shielding layer 156 isconformally deposited over top surface 158 and side surface 159 ofencapsulant 150 around semiconductor die 124, as shown in FIG. 4 h.Accordingly, shielding layer 156 covers a top portion and side portionof encapsulant 150 proximate to semiconductor die 124. Shielding layer156 is substantially flat across top surface 158 of encapsulant 150. Anoptional seed layer 160 can be conformally deposited over top surface158 and side surface 159 of encapsulant 150 prior to forming shieldinglayer 156. Shielding layer 156 can be Al, ferrite or carbonyl iron,stainless steel, nickel silver, low-carbon steel, silicon-iron steel,foil, conductive resin, conductive paste, and other metals andcomposites capable of blocking or absorbing EMI, RFI, and otherinter-device interference. Shielding layer 156 can also be a non-metalmaterial such as carbon-black or aluminum flake to reduce the effects ofEMI and RFI. Seed layer 160 can be made with Cu, Ni, nickel vanadium(NiV), Au, or Al. Shielding layer 156 and seed layer 160 are patternedand conformally deposited using an electrolytic plating, electrolessplating, sputtering, PVD, CVD, or other suitable metal depositionprocess. For non-metal materials, shielding layer 156 can be applied bylamination, spraying, or painting.

In FIG. 4 i, a portion of TSV interposer 140 is removed by grinder 162to expose conductive TSVs 142 opposite conductive layer 144.

In FIG. 4 j, a build-up interconnect structure 164 is formed overencapsulant 150 and semiconductor die 124. The build-up interconnectstructure 164 includes an electrically conductive layer or RDL 166formed using a patterning and metal deposition process such assputtering, electrolytic plating, and electroless plating. Conductivelayer 166 can be one or more layers of Al, Cu, Sn, Ni, Au, Ag, or othersuitable electrically conductive material. Conductive layer 166 a iselectrically connected to contact pads 132 for routing signals.Conductive layer 166 b is electrically connected through TSVs 142 toshielding layer 156 as a low impedance ground point. Other portions ofconductive layer 166 can be electrically common or electrically isolateddepending on the design and function of semiconductor die 124.

The build-up interconnect structure 164 further includes an insulatingor passivation layer 168 formed between conductive layer 166 forelectrical isolation using PVD, CVD, printing, spin coating, spraycoating, sintering or thermal oxidation. The insulating layer 168contains one or more layers of silicon dioxide (SiO2), silicon nitride(Si3N4), silicon oxynitride (SiON), tantalum pentoxide (Ta2O5), aluminumoxide (Al2O3), or other material having similar insulating andstructural properties. A portion of insulating layer 168 is removed byan etching process to expose conductive layer 166 for bump formation oradditional package interconnect.

In FIG. 4 k, an electrically conductive bump material is deposited overbuild-up interconnect structure 164 and electrically connected toconductive layer 166 using an evaporation, electrolytic plating,electroless plating, ball drop, or screen printing process. The bumpmaterial can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, and combinationsthereof, with an optional flux solution. For example, the bump materialcan be eutectic Sn/Pb, high-lead solder, or lead-free solder. The bumpmaterial is bonded to conductive layer 166 using a suitable attachmentor bonding process. In one embodiment, the bump material is reflowed byheating the material above its melting point to form spherical balls orbumps 170. In some applications, bumps 170 are reflowed a second time toimprove electrical contact to conductive layer 166. An under bumpmetallization (UBM) layer can be formed under bumps 170. The bumps canalso be compression bonded to conductive layer 166. Bumps 170 representone type of interconnect structure that can be formed over conductivelayer 166. The interconnect structure can also use bond wires, studbump, micro bump, or other electrical interconnect.

The semiconductor device shown in FIG. 4 k is singulated throughshielding layer 156 and TSV interposer 140 using saw blade or lasercutting tool 172 to separate individual semiconductor die 124 intoindividual Fo-WLCSP 174. Shielding layer 156 is electrically connectedto an external low impedance ground point through conductive TSVs 142and build-up interconnect structure 164.

FIG. 5 shows Fo-WLCSP 174 after singulation. Semiconductor die 124 iselectrically connected through TSV interposer 140 to conductive layer166 a of interconnect structure 164 and bumps 170. The wafer-level TSVinterposer 140 with shielding layer 156 provides higher productivity interms of manufacturing units per hour (UPH) at lower production cost forFo-WLCSP 174. The flat shielding layer 156 is readily formed overencapsulant 150 to block or absorb EMI, RFI, and other inter-deviceinterference. Shielding layer 156 provides EMI coverage over the top andaround the sides of semiconductor die 124 and routes EMI, RFI, and otherinterfering signals through TSV 142, conductive layer 166 b, and bumps170 to an external low-impedance ground point. Accordingly, the flatshielding layer 156 provides effective EMI and RFI shielding for the topand sides of semiconductor die 124.

In another embodiment, continuing from FIG. 4 d, an encapsulant ormolding compound 180 is deposited over TSV interposer 140 andsemiconductor die 124 using a paste printing, compressive molding,transfer molding, liquid encapsulant molding, vacuum lamination, spincoating, or other suitable applicator, as shown in FIG. 6 a. Encapsulant180 can be polymer composite material, such as epoxy resin with filler,epoxy acrylate with filler, or polymer with proper filler. Encapsulant180 is non-conductive and environmentally protects the semiconductordevice from external elements and contaminants.

In FIG. 6 b, a trench or channel 182 is cut completely throughencapsulant 180 and partially through TSV interposer 140 using saw bladeor laser cutting tool 184. Trench 182 is formed around a peripheral areaof semiconductor die 124, similar to FIG. 4 g. Trench 182 extendspartially through interposer 140 to a bottom of TSVs 142.

To reduce the effects of EMI and RFI, a shielding layer 186 isconformally deposited over top surface 188 of encapsulant 180 and intotrench 182 around semiconductor die 124, as shown in FIG. 6 c. Shieldinglayer 186 extends to a bottom of TSVs 142. Accordingly, shielding layer186 covers a top portion and side portion of semiconductor die 124.Shielding layer 186 is substantially flat across top surface 188 ofencapsulant 180. An optional seed layer 190 can be conformally depositedover top surface 188 of encapsulant 180 and into trench 182 prior toforming shielding layer 186. Shielding layer 186 can be Al, ferrite orcarbonyl iron, stainless steel, nickel silver, low-carbon steel,silicon-iron steel, foil, conductive resin, conductive paste, and othermetals and composites capable of blocking or absorbing EMI, RFI, andother inter-device interference. Shielding layer 186 can also be anon-metal material such as carbon-black or aluminum flake to reduce theeffects of EMI and RFI. Seed layer 190 can be made with Cu, Ni, NiV, Au,or Al. Shielding layer 186 and seed layer 190 are patterned andconformally deposited using an electrolytic plating, electrolessplating, sputtering, PVD, CVD, or other suitable metal depositionprocess. For non-metal materials, shielding layer 186 can be applied bylamination, spraying, or painting.

In FIG. 6 d, a portion of TSV interposer 140 is removed by grinder 192to expose conductive TSVs 142 and shielding layer 186.

In FIG. 6 e, a build-up interconnect structure 194 is formed overencapsulant 180 and semiconductor die 124. The build-up interconnectstructure 194 includes an electrically conductive layer or RDL 196formed using a patterning and metal deposition process such assputtering, electrolytic plating, and electroless plating. Conductivelayer 196 can be one or more layers of Al, Cu, Sn, Ni, Au, Ag, or othersuitable electrically conductive material. Conductive layer 196 a iselectrically connected to contact pads 132 for routing signals.Conductive layer 196 b is electrically connected to shielding layer 186as a low impedance ground point. Other portions of conductive layer 196can be electrically common or electrically isolated depending on thedesign and function of semiconductor die 124.

The build-up interconnect structure 194 further includes an insulatingor passivation layer 198 formed between conductive layers 196 forelectrical isolation using PVD, CVD, printing, spin coating, spraycoating, sintering or thermal oxidation. The insulating layer 198contains one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, or othermaterial having similar insulating and structural properties. A portionof insulating layer 198 is removed by an etching process to exposeconductive layer 196 for bump formation or additional packageinterconnect.

In FIG. 6 f, an electrically conductive bump material is deposited overbuild-up interconnect structure 194 and electrically connected toconductive layer 196 using an evaporation, electrolytic plating,electroless plating, ball drop, or screen printing process. The bumpmaterial can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu, solder, and combinationsthereof, with an optional flux solution. For example, the bump materialcan be eutectic Sn/Pb, high-lead solder, or lead-free solder. The bumpmaterial is bonded to conductive layer 196 using a suitable attachmentor bonding process. In one embodiment, the bump material is reflowed byheating the material above its melting point to form spherical balls orbumps 200. In some applications, bumps 200 are reflowed a second time toimprove electrical contact to conductive layer 196. An UBM layer can beformed under bumps 200. The bumps can also be compression bonded toconductive layer 196. Bumps 200 represent one type of interconnectstructure that can be formed over conductive layer 196. The interconnectstructure can also use bond wires, stud bump, micro bump, or otherelectrical interconnect.

The semiconductor device shown in FIG. 6 f is singulated throughshielding layer 186 and TSV interposer 140 using saw blade or lasercutting tool 202 to separate individual semiconductor die 124 intoindividual Fo-WLCSP 204. Shielding layer 186 is electrically connectedto an external low impedance ground point through build-up interconnectstructure 194.

FIG. 7 shows Fo-WLCSP 204 after singulation. Semiconductor die 124 iselectrically connected through TSV interposer 140 to conductive layer196 a of interconnect structure 194 and bumps 200. The wafer-level TSVinterposer 140 with shielding layer 186 provides higher productivity interms of manufacturing UPH at lower production cost for Fo-WLCSP 204.The flat shielding layer 186 is readily formed over encapsulant 180 toblock or absorb EMI, RFI, and other inter-device interference. Shieldinglayer 186 provides EMI coverage over the top and around the sides ofsemiconductor die 124 and routes EMI, RFI, and other interfering signalsthrough conductive layer 196 b and bumps 200 to an externallow-impedance ground point. Accordingly, the flat shielding layer 186provides effective EMI and RFI shielding for the top and sides ofsemiconductor die 124.

FIG. 8 shows an embodiment of Fo-WLCSP 206, similar to FIG. 7, with aninsulating or dielectric material 208 formed in trench 182 over the sidesurfaces of encapsulant 180 and TSV interposer 140 prior to formingshielding layer 186, see FIG. 6 b.

FIG. 9 shows an embodiment of Fo-WLCSP 210, similar to FIG. 7, with aconductive paste 212 deposited in trench 182. A shielding layer 214 andoptional seed layer 216 are conformally deposited over top surface 188of encapsulant 180. Shielding layer 214 is electrically connectedthrough conductive paste 212 and build-up interconnect structure 194 toa low impedance external ground point.

FIG. 10 shows another embodiment, similar to FIG. 7, with Fo-WLCSP 218mounted to substrate or PCB 220. Bumps 222 are formed between TSVs 142and bond pads or conductive traces 224 on substrate 220 for electricalinterconnect. Shielding layer 186 is electrically connected to a lowimpedance external ground point on substrate 220 with conductive paste228.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

1. A method of making a semiconductor device, comprising: providing asubstrate; forming a plurality of conductive vias partially through thesubstrate; mounting a semiconductor die over the substrate; depositingan encapsulant over the semiconductor die and substrate; forming atrench through the encapsulant around the semiconductor die and alignedwith one of the plurality of conductive vias; forming a shielding layerthat conforms to the encapsulant and extends to the substrate; removinga portion of the substrate to expose the conductive vias; and forming aninterconnect structure over the substrate opposite the semiconductordie, the interconnect structure being electrically connected to theconductive vias.
 2. The method of claim 1, further including: formingthe trench partially through the substrate; and forming the shieldinglayer in the trench partially through the substrate.
 3. The method ofclaim 1, further including forming a conductive layer over thesubstrate, the conductive layer being electrically connected to theconductive vias.
 4. The method of claim 1, further including forming aninsulating layer in the trench prior to forming the shielding layer. 5.The method of claim 1, further including depositing conductive paste inthe trench.
 6. The method of claim 1, wherein the shielding layer iselectrically connected to the interconnect structure.
 7. The method ofclaim 1, further including removing a portion of the substrate to exposethe shielding layer.
 8. A method of making a semiconductor device,comprising: providing a substrate; forming a plurality of conductivevias in the substrate; mounting a semiconductor die over the substrate;depositing an encapsulant over the semiconductor die and substrate;forming a trench through the encapsulant proximate to the semiconductordie and aligned with one of the plurality of conductive vias; forming ashielding layer over the encapsulant; and forming an interconnectstructure over the substrate opposite the semiconductor die, theinterconnect structure being electrically connected to the conductivevias.
 9. The method of claim 8, further including removing a portion ofthe substrate to expose the conductive vias.
 10. The method of claim 8,further including: forming the trench partially through the substrate;and forming the shielding layer in the trench partially through thesubstrate.
 11. The method of claim 8, further including forming aconductive layer over the substrate, the conductive layer beingelectrically connected to the conductive vias.
 12. The method of claim8, further including forming an insulating layer in the trench prior toforming the shielding layer.
 13. The method of claim 8, furtherincluding depositing conductive paste in the trench.
 14. The method ofclaim 8, wherein the shielding layer is electrically connected to theinterconnect structure.
 15. A method of making a semiconductor device,comprising: providing a through silicon via (TSV) substrate; mounting asemiconductor die over the TSV substrate; depositing an encapsulant overthe semiconductor die and TSV substrate; forming a trench through theencapsulant proximate to the semiconductor die; and forming a shieldinglayer that conforms to the encapsulant and extends into the trench andto the TSV substrate.
 16. The method of claim 15, further includingforming an interconnect structure over the TSV substrate opposite thesemiconductor die.
 17. The method of claim 15, further includingremoving a portion of the TSV substrate.
 18. The method of claim 15,further including forming a conductive layer over the TSV substrate. 19.The method of claim 15, further including forming an insulating layer inthe trench prior to forming the shielding layer.
 20. The method of claim15, further including depositing conductive paste in the trench.
 21. Amethod of making a semiconductor device comprising: providing a throughsilicon via (TSV) substrate; mounting a semiconductor die over the TSVsubstrate; depositing an encapsulant over the semiconductor die and TSVsubstrate; forming a trench through the encapsulant proximate to thesemiconductor die and partially through the TSV substrate; and forming ashielding layer over the encapsulant and into the trench partiallythrough the TSV substrate.
 22. The method of claim 21, further includingforming an interconnect structure over the TSV substrate opposite thesemiconductor die.
 23. The method of claim 21, further includingremoving a portion of the TSV substrate.
 24. The method of claim 21,further including forming a conductive layer over the TSV substrate. 25.The method of claim 21, further including forming an insulating layer inthe trench prior to forming the shielding layer.
 26. A method of makinga semiconductor device, comprising: providing a substrate; mounting asemiconductor die over the substrate; depositing an encapsulant over thesemiconductor die and substrate; forming a trench through theencapsulant proximate to the semiconductor die; and forming a shieldinglayer over the encapsulant that extends into the trench and to thesubstrate.
 27. The method of claim 26, further including forming aninterconnect structure over the substrate opposite the semiconductordie.
 28. The method of claim 26, further including removing a portion ofthe substrate.
 29. The method of claim 26, further including forming aconductive layer over the substrate.
 30. The method of claim 26, furtherincluding forming an insulating layer in the trench prior to forming theshielding layer.
 31. The method of claim 26, further includingdepositing conductive paste in the trench.